Electric apparatus



Dec. 223, i926.

P. R. DIJKSTERHUIS ELECTRIC APPARATUS Filed Feb. 18, 1925 WM 57' Ci Patented Dec; 28, 1 926. 7'

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Application fled February 10, 1925, Serial no. madam in Ietherlands 1 m 5, 1924.

This invention relates to electric apparatus comprising an incandescent'cathode of highly refractory metal such for example as tungsten, more particularly to the attachment of a filament for a high current i'ntensity to a leading-in wire in an electric apparatus which may be, for example, an electric incandescent lamp or an electric discharge tube. 1 I

It is known to connect a filament to its leading-in wire by welding. In the case of such a connection and especially if the filament is destined for a high current intensity, there easily occurs breakage of the filament near the weld,- which is probably due, at least. partly, to the filament becoming brittle near the weld.

tach a filament of lproposed already to vatighly refractory metal to a leading-in wire by bending the end of the latter and by clampin the filament in the loop thus formed. TlllS construction is, however, not suitable for current wires fo high current intensities.

According to the invention, one or each of the two ends of a filament is clamped in an aperture, split or groove provided in the end of a leading-in wire.

According to the invention, the end of the filament may be so bent as to form a loop which then 18 inserted into a groove in the leading-in wire, a pin which passes right across said groove being put through the eye of the loop. Moreover a wire is preferably wound round the free end of the loo protruding from the groove together with It has also been i the end of the filament.

According to the invention, the number of layers of wire windings may beso chosen as to increase towards the leading-in wire.

The accompanying drawingillustrates, by way of example, a construction showing the attachment of the filament in accordance .with the invention. In the drawing:

shewn in Figure 1 with the filament attached to it. v

Figure 3 represents a tubular Incandescent lamp provided witha filament attached according to theinvention.

According to the Fi drawing the end of a .fi amentl is so bent as to form a loop 2, which is inserted into a Figure 1 is a view of a leading-in-wire' res 1 and 2 of the A groove 3- provided in the end of a leadingin wire 4, A rivet 5 passes through the eye 7 of the loop 2, the free end 7 of which pro-- weld is increased, owing to which already the temperature of the wire in this place is decreased.v The helical wire 6 carrying itself also part of the current, still further increases this diameter so that the temperature decreases still more.

Figure 3 represents an incandescent lamp consisting of a glass vessel 10 into the wall of which leading-inwires 11 and 12 are hermetically sealed. The filament 13 is'attached to these leading-in wires in the mam ner shewn in the Figures 1 and 2. The vessel 10 may be highly evacuated in any known manner.

The invention may be applied with particular advantages to filaments for high current intensities, for example,-of more than 30 amperes. This attachment of the filament may not only be utilized in incandescent lampsfor a high candle power, but it may also be used advantageously, for example, in transmission tubes for wireless telegraphy or other discharge tubes for high capacit1es.

What I claim is: 2

An electric apparatus, comprising a filament of highly refractory metal, one or both of the two ends ofwhich is bent back upon itself so as to form a 100 which is inserted into a groove of the lea ing-in wire and is I POPIO REINDER DIJISI'ERHUIS. 

